1. Field of Disclosure
The present disclosure of invention relates to a thin film and a to a method of patterning the thin film so that the thin film has one or more patterned conductive portions and one or more patterned nonconductive portions. The present disclosure also relates to a thin-film transistor array substrate that includes the patterned thin film as defining pixel-electrodes of the substrate and to a method of manufacturing such a thin-film transistor array substrate.
2. Discussion of Related Technologies
Indium oxide compounds such as indium tin oxide (ITO), indium zinc oxide (IZO), etc. have been widely used in the past as materials of choice for making transparent electrodes in various electronic products including image forming and displaying products.
In recent years, it has become apparent that the indium element which serves as the base raw material for forming the various Indium oxide compounds (e.g., ITO, IZO, etc.) is becoming rare, hard to obtain, and more expensive. Thus, mass production of various electronic products that rely on a steady, reliable and cheap supply of Indium (In) is becoming problematic. Additionally, when transparent conductive thin films including indium oxide compounds are formed, for example by sputtering, a vacuum is typically needed, so that a manufacturing cost of electronic products based on such vacuum-requiring technology is increased. Also, the Indium oxide compounds tend to be brittle, thus durability is low. In order to begin solving such problems, development has begun on alternative materials that can function as transparent conductive electrodes.
More specifically, it has been proposed to use an ink including small metal wires and a binder (“micro-wires ink”). In one variation, it has been proposed that these small metal wires should be nano sized and used as a substitute for Indium oxide compounds. The proposed nano-wires ink is proposed to be easily coatable on a substrate under non-vacuum conditions so as to form transparent conductors. If this can be done, mass production manufacturing costs may be greatly decreased.
The proposed use of nano-wire ink should provide the advantage of it being easily blanket-wise formed as a transparent conductor layer on the whole surface of a substrate. Part of the proposal is that, after being blanket deposited, the nano-wire ink should be selectively etched through to thereby define nonconductive regions in the layer that holds the nano-wire ink. However, selectively etching of the nano-wire ink layer may bring new problems. For example, after a binder is formed for fixing (bonding) the nano metal wires of the ink to a substrate surface, the subsequent etching-through process may result in formation of acute undercut angles between a being-etched sidewall surface of the transparent thin film and a surface of the substrate. That is, due to sidewall etching effects, a large skew undercut may develop in the formed transparent pattern. Such an excessively skewed transparent pattern may easily become detached (partially removed, delaminated) from the substrate during or after the etch-based patterning process of the thin film, and as a result a manufacturing reliability of the transparent conductor film may be undesirably decreased.
It is to be understood that this background of the technology section is intended to provide useful background for understanding the here disclosed technology and as such, the technology background section may include ideas, concepts or recognitions that were not part of what was known or appreciated by those skilled in the pertinent art prior to corresponding invention dates of subject matter disclosed herein.